Explore EDR on iOS

9:23 - Create CGImage and Draw

// Create CGImage from HDR Image
let isr = CGImageSourceCreateWithURL(HDRImageURL, nil)
let img = CGImageSourceCreateImageAtIndex(isr, 0, nil)

// Draw into floating point bitmap context
let width  = img.width
let height = img.height

let info = CGBitmapInfo(rawValue: kCGBitmapByteOrder16Host |CGImageAlphaInfo.premultipliedLast.rawValue | CGBitmapInfo.floatComponents.rawValue)

let ctx = CGContext(data: nil, width: width, height: height, bitsPerComponent: 16,
    bytesPerRow: 0, space: layer.colorspace, bitmapInfo: info.rawValue)

ctx?.draw(in: img,
          image: CGRect(x: 0, y: 0, width: CGFloat(width), height: CGFloat(height)))

10:30 - Create floating point texture and Load EDR bitmap

// Create floating point texture
let desc = MTLTextureDescriptor()

desc.pixelFormat = .rgba16Float
desc.textureType = .type2D

let texture = layer.device.makeTexture(descriptor: desc)

// Load EDR bitmap into texture
let data = ctx.data

texture.replace(region: MTLRegionMake2D(0, 0, width, height),
                mipmapLevel: 0,
                withBytes: &data,
                bytesPerRow: ctx.bytesPerRow)

11:55 - CAMetalLayer properties

// Opt into using EDR
var layer = CAMetalLayer()
layer?.wantsExtendedDynamicRangeContent = true

// Use supported pixel format and color spaces
layer.pixelFormat = MTLPixelFormatRGBA16Float
layer.colorspace  = CGColorSpace(name: kCGColorSpaceExtendedLinearDisplayP3)

14:42 - UIScreen headroom

// Query potential headroom
let screen = windowScene.screen
let maxPotentialEDR = screen.potentialEDRHeadroom
if (maxPotentialEDR < 1.5) {
    // SDR path
}

// Query current headroom
func draw(_ rect: CGRect) {
    let maxEDR = screen.currentEDRHeadroom
    // Tone-map to maxEDR
}

// Register for Reference Mode notifications
let notification = NotificationCenter.default
notification.addObserver(self,
                         selector: #selector(screenChangedEvent(_:)),
                         name: UIScreen.referenceDisplayModeStatusDidChangeNotification,
                         object: nil)

// Query for latest status and headroom
func screenChangedEvent(_ notification: Notification?) {
    let status          = screen.referenceDisplayModeStatus
    let maxPotentialEDR = screen.potentialEDRHeadroom
}

16:54 - CAEDRMetadata and CAMetalLayer

// Check if EDR metadata is available
let isAvailable = CAEDRMetadata.isAvailable

// Instantiate EDR metadata
// ...

// Apply EDR metadata to layer
let layer: CAMetalLayer? = nil
layer?.edrMetadata = metadata

17:22 - Instantiating CAEDRMetadata

// HLG
let edrMetadata = CAEDRMetadata.hlg

// HDR10 (Mastering Display luminance)
let edrMetaData = CAEDRMetadata.hdr10(minLuminance: minLuminance,
                                      maxLuminance: maxContentMasteringDisplayBrightness,
                                      opticalOutputScale: outputScale)

// HDR10 (Supplemental Enhancement Information)
let edrMetaData = CAEDRMetadata.hdr10(displayInfo: displayData,
                                      contentInfo: contentInfo,
                                      opticalOutputScale: outputScale)